1. Field of the Invention
The present invention relates generally to an image scanning apparatus, and in particular, to a portable image scanning apparatus including a spatial modulator module.
2. Description of the Related Art
Recently, image scanning apparatuses using a laser light source, such as a semiconductor laser, have been suggested. Such an image scanning apparatus having a laser light source can be used in projectors, projector televisions, color scanners, and color printers. When the image scanning apparatus including a laser light source is used in projectors and projector televisions, the image scanning apparatus obtains an image on a screen. When the image scanning apparatus including a laser light source is used in color scanners and color printers, the image scanning apparatus reproduces an image on a drum.
The image scanning apparatus includes laser light sources, such as a semiconductor laser, for generating light beams having different visible wavelengths and a spatial light modulator for irradiating the light beams on each pixel according to the necessity. Various types of spatial light modulators are used for image scanning apparatuses.
For the spatial light modulators, diffraction gratings capable of modulating the characteristic of incident light are generally used. Examples of the diffraction gratings are: a planar grating light-valve (GLV) as a spatial light modulator described by David M. Bloom et al. in U.S. Pat. No. 5,459,610 issued Oct. 17, 1995; a grating electromechanical system (GEMS) described by Kowarz et al in U.S. Pat. No. 6,476,848 issued Jun. 25, 2002; an image scanning apparatus using a GLV is described by Paul K. Manhart et al. in U.S. Pat. No. 6,088,102 issued Jul. 11, 2000; and an image scanning apparatus using a GEMS is described by Kowarz et al. in U.S. Pat. No. 6,724,515 issued Apr. 20, 2004.
The above-described image scanning apparatus including a diffraction grating type spatial light modulator classifies incident light into a negative mode and a positive mode based on a mode of 0th-order and uses the modes except the mode of 0th-order. That is, a clear image can be realized by using the diffraction grating type spatial light modulator.
However, image scanning apparatuses are large and requires more power consumption, thus not an ideal for used as a portable device. In particular, a system configuration is complicated and bulkier to limit the mode of 0th-order as a separate configuration must be further included, as described in U.S. Pat. No. 6,724,515